CVE-2026-59900 Details
Description
Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, Netty's HTTP/2-to-HTTP/1.x translation layer (`Http2StreamFrameToHttpObjectCodec` and `InboundHttp2ToHttpAdapter`) fails to deduplicate or validate `Host` headers when an HTTP/2 client supplies both the `:authority` pseudo-header and a literal `host` header in a single HEADERS frame. The translator maps `:authority` to `Host` and separately copies the literal `host` header, producing an `HttpRequest` object containing two `Host` headers with attacker-controlled differing values. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.
A vulnerability exists in Netty's HTTP/2-to-HTTP/1.x translation layer, specifically in versions 4.2.0.Final through 4.2.15.Final and prior to 4.1.136.Final. The issue arises because the translation layer fails to properly deduplicate or validate 'Host' headers when an HTTP/2 client sends both the ':authority' pseudo-header and a literal 'host' header within the same HEADERS frame. This oversight allows the translator to create an 'HttpRequest' object that contains two 'Host' headers with differing values, both controlled by the attacker. As a result, this can lead to a request routing bypass.
Users can upgrade to Netty versions 4.1.136.Final or 4.2.16.Final to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 29, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/netty/netty/releases/tag/netty-4.1.136.Final | [email protected] | Release Notes |
| https://github.com/netty/netty/releases/tag/netty-4.2.16.Final | [email protected] | Release Notes |
| https://github.com/netty/netty/security/advisories/GHSA-c69g-56f8-xwqj | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-444 | Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| netty netty | < 4.1.136 >= 4.2.0, < 4.2.16 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Aug 6, 2026 | Initial Analysis | [email protected] |
| Jul 29, 2026 | CVE Modified | CISA-ADP |
| Jul 29, 2026 | New CVE Received | [email protected] |